Surveillance systems have a number of cameras which are used to monitor a variety of different physical areas (the cameras are primarily directed towards floor space, aisles, doorways, and loading docks). For example, in retail stores some of the more common physical areas that a retail store or supermarket may choose to monitor are the selling floor, the stock or storage area, and the shipping and receiving areas. The cameras can be fixed (providing only one view of the area) or fitted with pan, tilt and zoom features.
An operator (usually a security guard) sits at a console where the output of each camera is converted and displayed onto one or more monitors. The operator scans through the various views provided by the cameras looking for a target. A target is a predefined entity and may be anything of interest (e.g., an individual or a group of individuals exhibiting behavior indicative of theft or damage; merchandise in unexpected locations or in exposed situations; employees in unexpected or inappropriate places; etc.).
After locating the target, the operator attempts to maintain surveillance on that target until wrongful activity is detected and the individual committing the wrongful activity becomes a perpetrator. After a wrongful activity is spotted by the operator, the perpetrator is kept under constant surveillance until the perpetrator is taken into custody by the store security force or the police.
The importance of keeping a target under continuous surveillance cannot be understated. For example, if the target returns the merchandise to the selling area while out of sight, and the target is improperly detained, the store faces liability for false imprisonment.
If the cameras are equipped with mechanical pan, tilt and zoom features, the operator will have the option of locating and/or tracking a target by allowing the operator to adjust the camera via remote control to keep the target on the monitor at all times. The pan function moves a camera in a generally left-to-right or right-to-left direction; the tilt function moves the camera in a generally up and down direction; and the zoom is used to adjust the focal length of the camera's lens to provide expansive or close-up views (i.e., wide-angle to telephoto).
A variety of methods are used at the console to display the video signals input from a plurality of video cameras. In one type of surveillance system, a monitor is associated with each video camera. Accordingly, a security guard or operator of the system has in front of him a bank of monitors having a one-to-one correspondence with a particular video camera. This type of system has several drawbacks including the expense of having a monitor for each camera, physical space required to accommodate each individual monitor and the overwhelming task of the operator to review all monitors virtually simultaneously in order to identify an irregular event or intrusion.
Another system has one monitor and a plurality of video cameras in which the video signal from each camera is cycled through sequentially. The time each camera signal is viewable on the monitor is called the dwell. The particular camera order or sequence viewed on the monitor can be customized for a specific application. The sequence could be halted and the monitor could display the view from a single camera by overriding the sequence. The sequence can be restarted at a later time.
In addition, the dwell for each camera signal can be individually adjusted depending on the situation. For example, in a four camera system, the operator may view the video signal from camera one for five seconds, the video signal from camera two may then be displayed for nine seconds, the video signal from camera three may be displayed next for six seconds and finally, the signal from camera four may be viewed for fourteen seconds. After the fourth video signal is viewed, the system returns to the first video signal and the cycle is continuously repeated. The major draw back of this system is that the operator can only view the video signal from one camera at a time. Therefore, depending on the number of cameras and the period of time in which each camera is displayed on the monitor, it may take several minutes for the operator to view a particular area. Accordingly, if a target (e.g., an intrusion) is in an area monitored by a camera that is not currently being displayed on the monitor, the operator may completely miss the incident.
A variant of this last system is to have the operator manually control the dwell by pushing buttons that activate a video switch thereby allowing the operator to select a desired video signal (i.e., a desired camera corresponding to a physical area). However, a drawback of the manually selected one monitor/multiple camera switcher system is the need to use symbolic representations to indicate and differentiate the cameras and therefore the area covered by each camera. The operator must interpret each symbol in order to obtain the best camera view. It is difficult to track a fast moving target as it moves over floor space covered by several cameras. In this case, the operator must watch the direction the suspect is moving, determine the target's course and options, read and interpret the symbols, and press buttons to select the correct camera that has the target in its view. If the operator presses the wrong button, the target will be lost, thereby increasing the chances that the target will escape.
Even when the target is moving slowly, the operator may not react as quickly as needed to keep the target under continuous surveillance. Further, a VCR is normally used to record the target as it moves. If the operator pushes the wrong button, the VCR cannot record the crime or other irregular event.
Moreover, all new operators, and operators that have been trained on the system but are new to the site, require time to be trained on the symbolic mediated systems.